Leonard Zon, MD is internationally recognized for his pioneering work in stem cell biology and cancer genetics. He has been the preeminent figure in establishing zebrafish as an invaluable genetic model for the study of disease, focusing on blood and cancer development. Dr. Zon pioneered the field of developmental hematopoiesis. He undertook the first genetic screen to find zebrafish mutants with defects in blood formation during embryogenesis. He discovered ferroportin, an iron transporter in the yolk sac of the zebrafish. Ferroportin is also the mammalian placental and duodenal iron transporter. This gene is mutated in hemochromatosis (the first successful prediction of a human disease gene from zebrafish). Dr. Zon studied stem cell biology in zebrafish and discovered that prostaglandins stimulate blood stem cells in embryos and aids stem cell transplantation in fish and mice. PGE2 is in a phase II clinical trial based on this discovery. Dr. Zon developed the zebrafish as a cancer model. Using fish melanoma as an assay system, he identified the causative gene on chromosome 1 that is amplified in human melanoma, found that DHODH inhibitors suppress melanoma (being tested in a clinical trial), and visualized melanoma when initiates as a single cell in vivo. Dr. Zon led the zebrafish community in establishing the NIH Zebrafish Genome Initiative and started the Zebrafish Disease Model Society. As President of the International Society for Stem Cell Research, a society that he started, Dr. Zon has had a major impact on the country’s view of stem cell research.